Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 182206
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
306 PM MST THU DEC 18 2014

.SHORT TERM...TONIGHT THROUGH SATURDAY...SHORT WAVE RIDGE WILL
MOVE THROUGH OVERNIGHT...AND IN IT/S WAKE WE WILL BEGIN THE FIRST
OF TWO NOTABLE CHANGES IN THE WEATHER PATTERN IMPACTING THE
PACIFIC NW. STRONG MOIST FLOW WILL MOVE IN BEHIND THE SHORT WAVE
RIDGE. THIS WILL BEGIN A PERIOD OF MODERATE TO HEAVY PRECIP THAT
WILL LAST INTO THE LONG TERM. THE FIRST WAVE WILL MOVE IN FRIDAY.
WE HAVE CONTINUED THE TREND OF INCREASING POPS AS CONFIDENCE
INCREASES. PRECIP WILL SPREAD FROM WEST TO EAST TONIGHT...GETTING
INTO ALL OF SW IDAHO BY TOMORROW AFTERNOON. RAINFALL AMOUNTS WILL
RANGE FROM 0.10 TO 0.20 IN LOWER ELEVATIONS...WITH EVEN MORE AT
HIGHER ELEVATIONS. TEMPS WILL BE STILL BE ABOVE NORMAL...BUT
SEVERAL DEGREES COOLER THAN TODAY. FRIDAY NIGHT WE WILL SEE A
RELATIVE BREAK IN THE ACTION. ON SAT...AN EVEN WETTER SYSTEM WILL
BEGIN MOVING INTO THE REGION. LIGHT TO MODERATE RAINFALL WILL
MOVE INTO ERN OREGON EARLY IN THE DAY...AND INTO SW IDAHO MAINLY
IN THE AFTERNOON. CONDITIONS IN BOISE FROM MID AFTERNOON INTO THE
EARLY EVENING WILL BE COOL AND RAINY...WITH TEMPS IN THE LOWER
40S. HEAVIER PRECIP WILL COME SATURDAY NIGHT.

.LONG TERM...SATURDAY NIGHT THROUGH TUESDAY...A MOIST FLOW FROM
THE PACIFIC WILL KEEP OUR AREA MILD WET AND CLOUDY THROUGH MONDAY.
SNOW LEVELS WILL RANGE FROM 4000 TO 5000 FEET SATURDAY EVENING
THEN RISE TO AROUND 6500 FEET IN CENTRAL IDAHO AND AS HIGH AS 8000
FEET IN SOUTHEAST OREGON BY SUNDAY AFTERNOON. RAINFALL TOTALS OF
HALF AN INCH OR MORE ARE EXPECTED IN THE VALLEYS...FALLING MAINLY
SATURDAY NIGHT THROUGH SUNDAY EVENING. NEW SNOW ACCUMULATIONS OF
12 TO 18 INCHES ARE LIKELY ABOVE 6500 FEET BY MONDAY NIGHT IN THE
MOUNTAINS OF CENTRAL IDAHO AND BAKER COUNTY OREGON. MONDAY NIGHT
AND TUESDAY AN UPPER LEVEL RIDGE BUILDING NORTH AND EAST FROM
CALIFORNIA WILL BRING A DRYING TREND WITH SCATTERED SHOWERS
CONFINED MAINLY OVER THE MOUNTAINS. TEMPERATURES WILL AVERAGE
AROUND 15 DEGREES ABOVE NORMAL.

TUESDAY NIGHT THROUGH THURSDAY...THE REGION WILL BEGIN THIS
PERIOD IN A MOIST NORTHWESTERLY FLOW...BUT WILL COME UNDER THE
INFLUENCE OF A MOIST/COLD SHORTWAVE BY WEDNESDAY EVENING. THIS
SHORTWAVE WILL BRING A CHANCE OF PRECIPITATION TO THE ENTIRE
REGION AND WILL CONTINUE DOING SO UNTIL CHRISTMAS MORNING. AREAS
IN SOUTHEAST OREGON AND THE TREASURE VALLEY WILL BE THE FIRST TO
DRY OUT WHILE HIGHER ELEVATIONS AND THE MAGIC VALLEY WILL CONTINUE
TO EXPERIENCE A SLIGHT CHANCE OF PRECIPITATION THROUGH CHRISTMAS
NIGHT. PRECIPITATION COULD COME IN THE FORM OF SNOW /INCLUDING THE
VALLEYS AS TEMPERATURES AND SNOW LEVELS DROP/ BY WEDNESDAY NIGHT.
TEMPERATURES DURING THIS PERIOD WILL BEGIN ABOUT 5 DEGREES ABOVE
NORMAL BUT WILL DROP TO NORMAL BY THURSDAY.

&&

.AVIATION...SCATTERED MVFR SNOW SHOWERS WILL CONTINUE OVER THE
CENTRAL IDAHO MOUNTAINS THIS EVENING. AREAS OF SNOW WITH RAIN BELOW
4K FT MSL WILL SPREAD ACROSS EASTERN OREGON INTO THE CENTRAL IDAHO
MOUNTAINS AFTER 06Z AND ALL OF SOUTHWEST IDAHO AFTER 12Z. ON FRIDAY
EXPECT MOUNTAIN OBSCURATION...AREAS OF MVFR CEILINGS...AND LOCAL IFR
CONDITIONS ACROSS THE ENTIRE AREA WITH SNOW LEVELS AS LOW AS 3500 FT
MSL. SURFACE WINDS...EAST TO SOUTHWEST 5-10 KTS. WINDS ALOFT...
SOUTHWEST 15-25 KTS UP THROUGH 10K FEET MSL.

WEEKEND OUTLOOK...BRIEF IMPROVEMENT FRIDAY NIGHT WILL BE FOLLOWED BY
WIDESPREAD PRECIPITATION STARTING IN EASTERN OREGON SATURDAY MORNING
AND SPREADING ACROSS THE ENTIRE AREA BY SATURDAY EVENING. SNOW
LEVELS 3500-4500 FT MSL SATURDAY EVENING WILL RISE TO 6000-8000 FT
BY SUNDAY MORNING WITH PRECIPITATION CONTINUING THROUGH THE DAY.
SOUTHWEST SURFACE WINDS WILL INCREASE TO 20-30 KTS ACROSS THE HIGHER
TERRAIN OF SOUTHEAST OREGON AND SOUTHWEST IDAHO SATURDAY NIGHT AND
CONTINUE THROUGH SUNDAY.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.

&&

$$

WEATHER.GOV/BOISE

SHORT TERM...SP
LONG TERM....JT/AB
AVIATION.....JT


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